Stone (st)

The stone is a British unit of weight used almost only for people. In the UK and Ireland, someone might say they weigh "eleven stone four," which means 11 stone and 4 pounds. After a number, the plural usually stays stone.

NIST notes that the stone is still in common use for body weight in Britain, and that an earlier stone appears to have been 16 pounds (NIST Handbook 44, Appendix B). It is part of a family of larger British weights: 2 stone make a quarter, 8 stone make a hundredweight of 112 pounds, and 160 stone make a long ton (NIST Handbook 44, Appendix C).

A weight written as 12 st 6 lb means twelve stone plus six pounds. To turn it into pounds, multiply the stone by 14 and add the rest: 12 stone is 168 pounds, so the total is 174 pounds.

For kilograms, one stone is 6.35 kilograms, so the same person weighs about 78.9 kilograms. The stones to kilograms converter handles the math for any weight.

Outside the UK and Ireland, hardly anyone does, and the US never took up the stone for body weight. NIST points to one American trace of it, though: until World War II, flour was sold there by the barrel of 196 pounds, which is 14 stone (NIST Handbook 44, Appendix B).

Today Americans give body weight in pounds and most of the world uses kilograms, so a British weight in stone usually needs converting. The pounds to stones converter turns a US weight into British terms.